Remove or leave vinyl

I am getting ready to put new laminate down and I have a few questions.

1. I currently have sheet vinyl over a concrete slab. The vinyl is in decent shape (a few small cuts/tears and a couple of spots where it is coming up). Is it recommended to simply glue the spots back down and then lay the laminate over the top?

2. For the vapor barrier, should it simply go up to the wall or should it extend up the wall a bit? And is it taped to the wall?

3. This is a kitchen and the laminate needs to have a sealant in some places according to the manufacturer. Would it hurt to put sealant around the entire perimeter (I know it would probably be overkill)?

Thank you for any help you can offer! This is my first flooring project!